Homogeneous barrier height temperature dependence of Au/n-type GaAs Schottky diode

Abstract

The forward current–voltage (I–V) measurements upon temperature of Au/n-type GaAs Schottky barrier diodes (SBDs) have been carried out. The deduced zero-bias Schottky barrier height (Φ_0Bn) and the ideality factor (n) of Au/n-type GaAs over the temperature range 100–300 K have both shown non-ideal behavior. Indeed, Φ_0Bn and n exhibit opposite variation with temperature with respect to the ideal behavior. This non-ideal behavior has been attributed previously to the inhomogeneous nature of the Schottky barrier height (SBH) and successfully interpreted in terms of the thermionic-emission model. To elucidate this non-ideal behavior, the homogeneous zero-bias SBH ($\overline{\Phi }_{0Bn}$) was determined as a function of temperature using the Norde method, assuming the Schottky diode to be ideal (n = 1). Furthermore, the SBH temperature coefficient value is found to be $\Delta \overline{\Phi }_{0Bn} /\Delta T$ = − 0.18 meV/K which is negligible as compared to the one reported for the energy gap of GaAs, namely α = $\Delta$ E_g/$\Delta$ T = − 0.50 to − 0.60 meV/K. This feature is probably due to interface defects formed at the Au/n-GaAs contacts suggesting that the Fermi level is partially pinned at the interface between gold and n-type GaAs.